Dec 6, 2007
GaSb-based lasers with two-dimensional photonic crystal mirrors
Due to the unique property of creating a photonic stop band in an adjustable spectral range, photonic crystals can be used to guide light waves on the scale of their wavelength. This allows the realization of a variety of optoelectronic devices with high integration densities and a wide field of application.
In the chosen approach, 2D photonic crystals – cylindrically etched holes in tetragonal symmetry with diameters of around 300 nm and depths of 1.5 µm – have for the first time been successfully integrated in GaSb-based optoelectronic devices. When positioned at the end of ridge waveguide lasers these structures act as monolithically integrated mirrors with reflectivity well above 80%. The device’s properties show remarkable consistency with theoretical simulations and are in good agreement with values reported on different material systems. Therefore, the developed processing scheme paves the way for the transfer of virtually any approach based on 2D photonic crystals – for example, from GaAs or InP – to the GaSb material system.
Considering the accessible wavelength region of 1.8–3 µm GaSb-based diode lasers are of particular interest for highly integrated optoelectronic devices for gas-sensing applications, as many gases show characteristic absorption lines in this spectral range. Thus, immediate future work will focus on the development of such devices by combining short cavity lasers with built-in power detectors in a lab-on-a-chip manner.
About the author
Adam Bauer is a PhD student at the department of technical physics at the University of Würzburg. He is a member of the applied physics work group chaired by Prof. Dr Alfred Forchel, which is doing research in the field of low-dimensional optoelectronic devices based on III-V-semiconductors. The work was part of the author’s diploma thesis.